Ripple reduction circuit for sequential linear LED drivers
A ripple reduction circuit is provided. The ripple reduction circuit may include a ripple capacitor configured to drive at least a first segment of a string of light emitting diodes (LEDs), a first diode having an anode coupled to the ripple capacitor, and a cathode configured to be coupled to an input end of the first LED segment, a second diode having a cathode coupled to the ripple capacitor and the anode of the first diode, and an anode configured to be coupled between the first LED segment and a second LED segment of the string of LEDs, a third diode having an anode coupled to the ripple capacitor, and a cathode configured to be coupled to a last LED segment of the string of LEDs, and a fourth diode having a cathode coupled to the ripple capacitor and the anode of the third diode.
1. A ripple reduction circuit comprising:
a ripple capacitor configured to drive at least a first segment of a string of light emitting diodes (LEDs);
a first diode having an anode coupled to the ripple capacitor, and a cathode configured to be coupled to an input end of the first LED segment;
a second diode having a cathode coupled to the ripple capacitor and the anode of the first diode, and an anode configured to be coupled between the first LED segment and a second LED segment of the string of LEDs;
a third diode having an anode coupled to the ripple capacitor, and a cathode configured to be coupled to a last LED segment of the string of LEDs; and
a fourth diode having a cathode coupled to the ripple capacitor and the anode of the third diode.
2. The ripple reduction circuit of claim 1 , wherein the fourth diode comprises an anode coupled to ground.
3. The ripple reduction circuit of claim 1 , wherein the fourth diode comprises an anode configured to be coupled to a voltage divider circuit that is coupled to a single control point of an LED driver circuit.
4. The ripple reduction circuit of claim 3 , wherein the LED driver circuit comprises:
a first current regulator coupled to the string of LEDs between the first segment and second segment thereof, and coupled to the anode of the second diode; and
a fourth current regulator coupled to the last segment of the string of LEDs, and coupled to the cathode of the third diode.
5. The ripple reduction circuit of claim 4 , wherein the LED driver circuit further comprises:
a second current regulator coupled to the string of LEDs between a second segment of the string of LEDs and a third segment of the string of LEDs; and
a third current regulator coupled to the string of LEDs between the third segment and the last segment thereof.
6. The ripple reduction circuit of claim 3 , wherein the LED driver circuit comprises:
a first current regulator coupled to the string of LEDs between the first LED segment and the second LED segment, and coupled to the anode of the second diode; and
a fourth current regulator coupled to the last LED segment, and coupled to the cathode of the third diode.
7. The ripple reduction circuit of claim 6 , wherein the LED driver circuit further comprises:
a second current regulator coupled to the string of LEDs between the second LED segment and a third LED segment of the string of LEDs; and
a third current regulator coupled to the string of LEDs between the third LED segment and the last LED segment.
8. A ripple reduction circuit comprising:
a ripple capacitor configured to drive at least a first segment of a string of light emitting diodes (LEDs);
a first diode having an anode coupled to the ripple capacitor, and a cathode configured to be coupled to an input end of the first LED segment;
a second diode having a cathode coupled to the ripple capacitor and the anode of the first diode, and an anode configured to be coupled between two LEDs of the first LED segment;
a third diode having a cathode coupled to the ripple capacitor, and an anode coupled to ground; and
a fourth diode having an anode coupled to the ripple capacitor and a cathode coupled to two LEDs of a fourth LED segment of the string of LEDs.
9. The ripple reduction circuit of claim 8 , further comprising a first current regulator coupled to the string of LEDs between the first LED segment and a second LED segment of the string of LEDs.
10. The ripple reduction circuit of claim 9 , further comprising a second current regulator coupled to the string of LEDs between the second LED segment and a third LED segment of the LED string.
11. The ripple reduction circuit of claim 10 , further comprising a third current regulator coupled to the string of LEDs between the third LED segment and the fourth LED segment.
12. The ripple reduction circuit of claim 11 , further comprising a fourth current regulator coupled to the fourth LED segment.